How Antioxidants Improve Polymer Stability
Why Polymers Degrade Through Oxidation
Polymer oxidation follows a chain reaction. Heat, UV radiation, mechanical shear, or metal contamination generates free radicals. These react with oxygen to form peroxy radicals, which continue the chain. Without antioxidants, this leads to yellowing, embrittlement, melt flow changes, and surface degradation.
Primary Antioxidants: Radical Scavengers
Hindered phenol antioxidants (Antioxydant 1010, 1076, 1098) donate hydrogen atoms to peroxy radicals, converting them into stable molecules and breaking the chain reaction. They are the first line of defence against oxidative degradation.
Secondary Antioxidants: Hydroperoxide Decomposers
Secondary antioxidants address hydroperoxides — the key intermediates that reinitiate radical chains if left unchecked:
- Phosphites (Antioxydant 168): Fast-acting at high melt temperatures, excellent processing stabilizers
- Thioesters (DSTDP, DLTDP): Cost-effective long-term thermal aging protection
Synergistic Systems
- Antioxydant 1010 + 168: Most widely used polyolefin system
- Antioxydant 1010 + DSTDP: Cost-effective long-term stabilization in PP/PE
- Antioxydant 1010 + 168 + HALS: Full stabilization for outdoor applications
Polymer-Specific Selection
- PP: 1010 + 168 at 0.1–0.3% combined
- PE: Combined systems; confirm by OIT testing for pipe/geomembrane applications
- Engineering plastics: Grades stable at 250–300°C (Antioxydant 168 is key at these temperatures)
FAQ
Do antioxidants provide UV protection?
Non. Antioxidants address thermal oxidative degradation only. For outdoor applications, UV absorbers and HALS stabilizers must be added separately.
Contact SUNCHEM
SUNCHEM's team can help recommend the right antioxidant system for your polymer and application. Contactez-nous for technical support and samples.